The native fish that inhabit the freshwater system of Puerto Rico are amphidromous (part of their lifes occur in the river and part on the ocean) or catadromus (migrate from the stream to the ocean to reproduce). These species utilize upper and lower reaches of the streams, but some of them have the adaptation to migrate through the vertical wall of the water falls. In general the lower reaches are dominated by mountain mullet (Agnostomos monticula), big mouth sleeper (Gobiomorus dormitor), smallscaled spinycheek sleeper (Eleotris perniger), omnivorous goby (Awaous taiasica), and the American eels (Anguilla rostrata); while the upper parts of the streams are inhabited by river gobies (Sicydium plumieri). Sicydium and Awaous have modified pectoral fins that use to climb the waterfalls.

  • Natural History. Native fish are river-estuarine dependant species that have a life cycle with embryonic and larval stages that depend of the estuary or marine salinity to complete their metamorphosis (amphidromous). These fishes mature and reproduce in freshwater, and swim down to the estuary to release either eggs or larvae; they are iteroparous (they do not die after spawning) and can spawn several times during their life cycle. They are reproductively active across the year. These species are important component of the estuarine and river food webs where they are the dominant predator and scavenger consuming a wide range of freshwater organisms. As well, these fishes constitute the food for other fish, crabs, birds, boas, and humans that apparently are the responsible for the recent decline in the abundance of these organisms.
Omar Pérez,
Oct 3, 2011, 10:03 PM